Low power modes for new board - Sleep and Deep-sleep

[Praneethsvch]

4 sensor operational mode types are available for use

Run mode

• by default the sensor is in run mode after a system power-on or reset

Sleep mode

• Several sleep modes are available: Sleep, LPRun, LPSleep, Stop0, Stop1, and Stop2 modes

Sleep mode

• CPU clock is off
• All peripherals including CPU core peripherals (among them NVIC, SysTick) can run and wake up the CPU when an interrupt or an event occurs

Low-power run mode (LPRun)

• System clock less than 2MHz
• Code is run from SRAM or FLash
• Regulator is in low-power mode

Low-power sleep mode (LPSleep)

• entered from the LPRun mode

Stop 0 and Stop 1 modes

• SRAM1, SRAM2 and all registers values are retained
• PLL, MSI, HSI16, and HSE32 are disabled
• LSI and LSE running
• Sub-GHz radio may remain active independent from CPU
• Stop0 -> Power regulator is on for faster wakeup times but at the expense of higher power consumption
• Stop 1 -> Uses Low-power regulator instead
• Can exit into - MSI uptown 48MHz or HSI 16

Stop 2 mode

• SRAM1, SRAM2 and some registers values are retained
• rest almost similar to Stop0 and 1

Standby mode

• VCORE is off
• LSI and LSE are running
• Only SRAM2 contents are possible to retain after wake-up
• RTC can be active
• Sub-GHz radio may remain active independent from CPU

Shutdown mode

• VCORE is off
• only LSE can be kept running

Future todo

Currently sensor is 1 min duty cycle with successive readings during on time just before RX, so a single best sleep-mode should do. But with more operations and interrupt/timer wake-ups the sleep modes should be carefully chosen to get lowest power consumptions

• Wakeup and Sleep Power overheads
• Tradeoffs using modes between sensor operations

Reference

Full functionalities in Datasheet on pg 29